Automatic milking systems (AMS) are well known in the art. The current implementations of AMS are almost entirely with housed cows. Cows are bedded and fed in a large barn that also houses the AMS. Cows learn to circulate freely the short distance between their cubicles and the AMS unit, a prime motivator being in-bail feeding while they are being milked in the AMS. The cows only need to move comparatively short distances, perhaps 20–30 m within the housing system to the AMS.
Many cows around the world are not housed in this fashion, however, but freely graze pasture. In New Zealand and Australia, in particular, there is no housing of cows, they spend all their time on pasture. These pasture-based systems are very extensive and often require the cows to walk considerable distances to be milked in conventional milking systems. This can be up to 2–3 km walking distance, and they normally do this twice a day.
Usually such extensive pasture systems also require a systematic rotation around paddocks, typically one paddock per day, to most effectively utilise the feed that is grown.
Implementation of AMS under extensive pasture systems is a challenge and has not previously been achieved in the context of a pasture based system. Limited combination of AMS with grazing has been implemented in Europe usually with housing of the cows.
The cows are normally housed, but are let out for a limited period to adjacent paddocks.
In such cases pasture typically contributes less than 30% of the total diet. In New Zealand, and many Australian scenarios, pasture will contribute more than 80% of the total dietary intake over the lactation.
More remote paddocks have been used in some systems (ie up to 400 m) and milking has been achieved by using the motivator of shifting the drinking water to the other side of the AMS. Where the principal feed is pasture, this may not be an acceptable strategy, particularly from an animal ethics viewpoint. It may also require cows to walk considerably distances to access water, depending on how frequently they require to drink.
U.S. Pat. No. 4,508,058 discloses a milking system for use where cows are allowed to find their own way toward a stall, known as “going loose”. The system includes a computer that identifies a transponder tagged cow when it enters a robotic milking stall. If the computer determines feeding is required then the cow is fed. If the computer determines milking is required, the cow is retained and milked. If neither of these criteria are met, the cow is released. The cows are tempted into the stalls by the promise of food.
The context of “go loose” as used in U.S. Pat. No. 4,508,058 is certainly not that of trafficking to remote pasture sites.
U.S. Pat. No. 5,771,837 describes a milking parlour where cows are free to wander around a feeding trough that runs almost to each end of the parlour. At one end the cows can pass around the trough. At the other end the cows must enter a selection compartment and are tempted to do so by a fodder concentrate. In the selection compartment a cow is identified by its transponder and if it meets one of the criteria for milking such as lactation it is released into the milking stall. If it does not meet the criteria it is allowed to pass through a separate gate leading to the other side of the feeding trough whereby it begins a circuit of the parlour again. Once milking of a selected cow is complete it is released at the same place. The fact that another circuit of the parlour is required before a cow can re-enter the selection compartment aims to prevent cows that are not eligible for milking from re-entering it. This system does not attempt to reduce total walking distance.
This does not envisage remote, far-field pre-selection of cows on the basis of normal behaviours such as drinking, for direction to the AMS or subsequent transfer to a new area of pasture, and minimisation of walking distance which can be extensive in remote pasture feeding.
U.S. Pat. No. 6,062,164 teaches of a “lying and walking” area connected by a first polling gate to a waiting area and a feeding and watering area. Cows entering the gate are identified and directed towards the former area if milking is required and towards the latter if it is not.
Once in the feeding and watering area the cow can only return to the lying and walking area. Once in the waiting area the cow can pass into a lane leading to one or more milking stalls. Upon leaving the stall a cow enters a second polling gate and may be directed to a segregation area if, for example, mastitis is detected, directed to the feeding and watering area if milking was successful, or directed back to the waiting area for reentry into a milking stall if milking was unsuccessful. Also disclosed is the fact that it has been found in practice that it is necessary to coerce animals to enter the first polling gate, such as by using moveable electric fences.
U.S. Pat. No. 6,148,766 discloses identification of an animal by a computer system which opens the doors of a milking stall if the animal is to be milked and luring the animal into the stall using food and is of general relevance only.
None of these implementations of AMS with grazing have been on the scale that is required in a pasture based dairying system nor have any suggested a practical means for implementing AMS on an extensive pasture based grazing system.
It is desirable that any AMS system is designed to facilitate a cow's adaption to it. In any multiple paddock system it would be desirable that the system has a high degree of symmetry. This way a cow can be familiar with the layout no matter what paddock she is in.
An automated system is required for pasture grazing cows that can determine if such cows are due to be milked so that AMS technology can be successfully applied to pasture grazing cows. Any such system of the prior art requires a cow to walk to the AMS before it is selected, which is not feasible for pasture based dairying systems. Special systems are required to make AMS functional under these conditions.
It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or at least to provide a useful alternative.